Structural body and core

ABSTRACT

According to one embodiment, there is provided a structural body including a core composed of fiber and a support, which is a component of the core and is in contact with the core.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation application of PCT Application No.PCT/JP2016/058590, filed Mar. 17, 2016, and is based upon and claims thebenefit of priority from Japanese Patent Application No. 2015-053452,filed Mar. 17, 2015, the entire contents of all of which areincorporated herein by reference.

FIELD

Embodiments of the present invention relate to a structural bodyincluding a core made of fiber and a core that composes the structuralbody.

BACKGROUND

Conventionally, a structural body including a core made of fiber hasbeen considered. As the fiber that composes this type of structuralbody, for example, a fine fiber made of polymeric material such as thosedisclosed in Japanese Patent Application KOKAI Publication No.2002-249966 is considered. However, there is a problem in that thestructural body with a core composed of fiber has a weak structuralstrength, due to its structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a configurational example of astructural body according to an embodiment.

FIG. 2 is a cross-sectional view showing a configurational example of astructural body according to an embodiment.

FIG. 3 is a cross-sectional view showing a configurational example of astructural body according to an embodiment.

FIG. 4 is a perspective view showing an example of a support included ina structural body.

FIG. 5 is a perspective view showing another example of a supportincluded in the structural body.

FIG. 6 is a cross-sectional view showing a configurational example of astructural body according to an embodiment.

FIG. 7 is a cross-sectional view showing a configurational example of astructural body according to an embodiment.

FIG. 8 is a cross-sectional view showing an example of a laminatedstructure of a laminate film.

FIG. 9 is a pattern diagram showing an example of use as a biomaterialsheet.

FIG. 10 is an electron micrograph showing an example of an orientedcollagen sheet.

FIG. 11 is a schematic view showing an example of an insulating materialand an insulating auxiliary material.

FIG. 12 is a schematic view showing an example of use as a water dropletimpact absorbing member.

FIG. 13 is a cross-sectional view taken along line XIII-XIII of FIG. 12.

FIG. 14 is a schematic view showing an example of use as an adhesivelayer.

FIG. 15 is a schematic view showing an example of use as a surface layerof a barrier membrane.

FIG. 16 is a schematic view showing a projection view of a fiber in anobservation direction.

DETAILED DESCRIPTION

According to one embodiment, there is provided a structural bodyincluding a core composed of fiber and a support, which is a componentof the core, and is capable of suppressing deformation of the core.

According to another embodiment, there is provided a structural bodyincluding at least one porous layer that includes an electrolyte and afiber including a thermosetting resin.

According to yet another embodiment there is provided a structural bodyincluding a stack that includes plural porous layers. The plural porouslayers include a resin with a density of 0.5 g/cm³ to 3 g/cm³ and afiber with an average diameter of 30 nm or more and less than 5 μm. Aporosity of the porous layers is within a range of 45% to 95%.

Furthermore, according to still another embodiment, there is provided astructural body including a core composed of fiber and a support, whichis a component of the core and is in contact with the core.

Hereinafter, an embodiment will be described with reference to thedrawings. A structural body 10 illustrated in FIG. 1 has a structure inwhich a core 11 that composes a main body portion of the structural body10 is housed in a covering member 12. The core 11 includes a fiber 13and a support 14. The covering member 12 composes a surface portion ofthe structural body 10. The covering member 12 is composed of any of ametal material, an organic material, and an inorganic material or asheet material formed of a combination of these materials. In thepresent case, the covering member 12 is configured to have a sac-likeshape which can house the core 11 formed of the fiber 13 and the support14. In the covering member 12, the support 14 is covered with the fiber13. The covering member 12 need not cover the entire core 11, but may beconfigured to cover a portion of the core 11.

The fiber 13 is formed of randomly entangled resin fibers. In thepresent case, the fiber 13 is molded by an electrospinning method. Thefiber 13 formed by the electrospinning method becomes a thin fiberhaving an outer diameter of about 0.1 nm to 10 μm, and at the same time,a long fiber having a length that is equal to 1000 times or more of theouter diameter, for example. Further, the fiber 13 formed by theelectrospinning method is not entirely linear, but has a randomly curvedcrimp shape. Accordingly, there is more entangling of the fibers witheach other.

In the present case, the fiber 13 is formed of an organic polymer whosedensity is smaller than that of glass. By forming the fiber 13 with apolymer having a density smaller than that of glass, the weight of thefiber 13 can be reduced. The fiber 13 may be formed by mixed spinning ofone or two or more polymers selected from polystyrene, polycarbonate,polymethyl methacrylate, polypropylene, polyethylene, polyethyleneterephthalate, polybutylene terephthalate, polyamide, polyoxymethylene,polyamide-imide, polyimide, polysulfone, polyether sulfone, polyetherimide, polyether ether ketone, polyphenylene sulfide, modifiedpolyphenylene ether, syndiotactic polystyrene, liquid crystal polymer,urea resin, unsaturated polyester, polyphenol, melamine resin, epoxyresin, and a copolymer including these materials.

In the case where the fiber 13 is formed by the electrospinning method,the above polymers are made into solutions. Examples of a usable solventinclude a volatile organic solvent such as isopropanol, ethylene glycol,cyclohexanone, dimethylformamide, acetone, ethyl acetate,dimethylacetamide, N-methyl-2-pyrrolidone, hexane, toluene, xylene,methyl ethyl ketone, diethyl ketone, butyl acetate, tetrahydrofuran,dioxane, and pyridine; and water. Further, the solvent may be one kindselected from the above solvents or plural kinds may be mixed. Thesolvent that may be applied to the embodiment is not limited to theabove solvents. The above solvents are shown only as examples.

In the case where the fiber 13 is formed by the electrospinning method,there can be more entangling of the fibers with each other. Thus, it ispossible to spin and simultaneously form a nonwoven fabric fiber sheet.Further, by forming the fiber 13 via the electrospinning method, it ispossible to obtain a fiber diameter of a micro-order to nano-order.

The fiber 13 preferably has a diameter of about 5 μm or less, morepreferably a diameter of 1 μm or less (i.e., a nano-order diameter).Further, various kinds of inorganic fillers such as silicon oxide, metalhydroxide, carbonate, sulfate, and silicate may be added to the fiber13. As the inorganic fillers to be added, for example, wollastonite,potassium titanate, xonotlite, gypsum fibers, aluminum borate, MOS(basic magnesium sulfate), aramid fiber, carbon fiber, glass fiber,talc, mica, and glass flake are considerable.

The support 14 is composed of, for example, an acrylic resin materialand has strength capable of enduring stress. In the present case, thesupport 14 has a porous structure having fine voids. This results inreduction of weight of the support 14, and in turn, the weight of thecore 11 and the structural body 10 can be reduced. The support 14 has afunction of suppressing deformation of the core 11 due to stress andalso a function of suppressing compression of the fiber 13. By includingthe support 14, the shape of the core 11 made of the fiber 13, in otherwords, the shape of the structural body 10 can be stably maintained.Further, the strength of the core 11 can be improved, and in turn, thestrength of the structural body 10 can be improved. The support 14preferably has a shape in which angular portions are rounded. In thiscase, it is possible to relax the force applied from the angularportions of the support 14 to the covering member 12.

The structural body 10 includes the support 14 in the core 11, wherebythere is reduction in the amount of the fiber 13 that is used ascompared to one in which the entire core 11 is formed of the fiber 13.Further, the structural body 10 includes the support 14 in the core 11,whereby the thickness of the fiber layer made of the fiber 13 issuppressed. In the case where an external force of some kind is appliedto the core 11, the fiber 13 that compose the core 11 is compressed incorrespondence to the applied force. However, in the structural body 10according to the embodiment, the thickness of the fiber layer presentbetween the covering member 12 and the support 14, namely, the amount ofthe fiber 13 is suppressed. Thus, as compared to the structure in whichthe fiber 13 is housed in the whole interior of the covering member 12,the compression amount of the fiber 13 can be suppressed.

In the structural body 10 according to the embodiment, with regard to astructural body 10 including a core 11 of a fiber 13, a support 14 forsuppressing deformation of the core 11 is provided in the core 11.Accordingly, as compared to the structure in which the entire core isformed of a fiber, it is possible to improve the strength of the core11, and in turn, it is possible to improve the strength of the entirestructural body 10.

In the structural body 10 according to the embodiment, as the support 14is porous, the weight of the support 14 can be reduced, and in turn, theweight of the core 11 and the structural body 10 can be reduced.

The structural body according to the embodiment includes a core made offiber and a support, which is a component of the core, and suppressesdeformation of the core. According to such a structure, it is possibleto improve the strength of a structural body that includes a core madeof fiber.

For example, the support 14 may be made of, for example, a metalmaterial or an inorganic material, in addition to a resin material, andmay be employed with the material changed as appropriate. Further, thefiber 13 need not be a resin fiber, and may be a glass fiber, or may bea fiber formed of a material including an organic compound. In the casewhere the fiber is composed of a fiber including an organic compound,the organic compound may be an organic compound derived from anorganism. Further, the structural body 10 may be one in which theinterior of the covering member 12 housing the core 11 is depressurized.

The structural body according to the embodiment can be used for variousapplications such as artificial joints, filters, pillows, packingmaterials for valuable items, and beds. Further, structural body can beused for seats such as seats mounted in automobiles, bullet trains (alsoknown as Shinkansen), and airplanes; and child seats. Furthermore, itcan be used for masks, adhesive bandages, conductive sheets, or thelike. In the case of using the structural body according to theembodiment for, for example, artificial joints or adhesive bandages, thestructural body is favorable as a member for providing a space forkeeping moist. The structural body according to the embodiment can notonly be used in air, but can also be used in a liquid. Further, thestructural body can be used as a separator between mutually differentenvironments.

The structural body of the embodiment will be further described.

According to the embodiment, there is provided a structural bodyincluding a porous layer.

The porous layer is one where one or plural fibers are accumulated,deposited, stacked, or assembled. In the porous layer, the fibers areentangled and are in contact with one another at plural places formingcontact points. The fibers are disposed three-dimensionally in theporous layer. At the contact points, the fibers may be adhered or weldedto each other or may be neither adhered nor welded to one another. Theorientation of the fibers at the contact points may change due toexternal force applied to the porous layer, or the like. The porouslayer may be considered as having a non-woven fabric shape.

The pores present in the porous layer may be any of independent pores,continuous pores, and through holes. Plural kinds of pores may bepresent (e.g., independent pores and continuous pores).

The fiber in the porous layer may include (a) an electrolyte and a firstfiber including a thermosetting resin and (b) a second fiber thatincludes a resin with a density of 0.5 g/cm³ to 3 g/cm³ and has adiameter of 30 nm or more and less than 5 μm. Both of the first fiberand the second fiber may be included in the same porous layer. The firstfiber and the second fiber may be the same fiber.

In a porous layer including the first fiber, the second fiber, or thefirst fiber and the second fiber, the average diameter, entanglingdegree, and arrangement of the fibers can be freely changed. Thus, it ispossible to provide a structural body which can arbitrarily change thecompressive strength. The structural body can be used as aheat-insulating element, a biomaterial sheet, an insulating material, aninsulating auxiliary material, a water droplet impact absorbing member,an adhesive layer, a barrier membrane or the like, in addition to theapplications as described above.

Since the compressive strength can be increased in the porous layerincluding the first fiber, the second fiber with a density of 1 g/cm³ to2 g/cm³, or both of these fibers, it is possible to reduce crushing ofpores due to compression. As a result, the porous structure of theporous layer can be maintained for a long period of time, and thus themorphological stability of the porous layer is improved. Therefore, itis possible to realize a structural body having high morphologicalstability and excellent compressive strength. The structural body can beused as a heat-insulating element, a biomaterial sheet, an insulatingmaterial, an insulating auxiliary material, a water droplet impactabsorbing member, an adhesive layer, a barrier membrane or the like, inaddition to the applications as described above.

As a result of improvement in the compressive strength of the porouslayer, the amount of the fiber that is used in the porous layer can bereduced, and the porosity can be increased. Accordingly, the porouslayer can be configured to have a structure with a small fiber diameterand high porosity to enable the heat conductivity to be low, and thusthe insulation properties of the structural body can be improved.

The thermosetting resin included in the first fiber is preferably a maincomponent of the fiber. Here, main component means a component with thehighest proportion among the components of the fiber. The amount of thethermosetting resin included in the fiber is preferably 50 wt % or more.Accordingly, the compressive strength of the porous layer can beimproved.

The range of the dielectric constant of the thermosetting resin ispreferably from 1 to 1000. Accordingly, a porous layer with highcompressive strength and low heat conductivity is obtained. This isbecause control of the fiber formation becomes easy, when producing theporous layer by the electrospinning method, and thus, it becomes easy tomake adjustments, such as making the fiber diameter smaller, making thearrangement (or entangling) of the fiber complicated, and the like. Amore preferable range of the dielectric constant is from 50 to 1000. Thedielectric constant can be measured, for example, by a resonator method.

An example of the thermosetting resin includes an epoxy resin. Thedielectric constant of the epoxy resin is within a range of 1 to 1000.

The electrolyte contributes to improvement in the compressive strengthand insulation properties of the porous layer including an epoxyresin-including fiber. The reason therefor is as follows. Theelectrolyte can increase the dielectric constant and electricalconductivity of the raw material solution used when producing a porouslayer by the electrospinning method. As compared to the case of addingno electrolyte, the dielectric constant can be increased by about 2 to100-fold, for example. As a result, control of the fiber formation inthe electrospinning step becomes easy, and it becomes easy to makeadjustments, such as making the fiber diameter smaller, making thearrangement (or entangling) of the fiber complicated, and the like. Inaddition to such an effect, the electrolyte can increase theconductivity of the epoxy resin-including fiber. Examples of theelectrolyte include inorganic salts, ammonium salts, and ionic liquids.The electrolyte desirably has excellent affinity with thermosettingresins and excellent solubility in solvents. Examples of the inorganicsalts include LiBr, LiCl, NaCl, LiCl, MgCl₂, NaOH, KMnO₄, and K₂CrO₄.Further, examples of the ammonium salts include NH₄Cl and NH₄Br. On theother hand, examples of the ionic liquids include 1-butyl-3-methylimidazolium hexafluorophosphate. The electrolyte may be one kind or twoor more kinds. LiBr has excellent solubility in an organic solvent(e.g., cyclohexanone) used as a solvent for a raw material solution.LiBr also has an advantage of being inexpensive. Further, LiBr isthermally and chemically stable.

The amount of the electrolyte included in the first fiber may be withina range of 0.01 wt % to 10 wt %. When the amount of the electrolyteincluded is low, fibers having a thin diameter are not obtained. On theother hand, when the amount of electrolyte included is too high, thereis concern that the amount of thermosetting resin included becomesinsufficient, whereby the compressive strength of the porous layerdecreases. More preferably, the range is from 0.1 wt % to 2 wt %.

The average diameter of the first fiber is preferably within a range of30 nm to 5 μm. Thus, the heat conductivity of the porous layer can bereduced, thereby increasing heat-insulating properties. Further, thepressure loss of the porous layer can be reduced. A more preferablerange is 30 nm or more and less than 5 μm, an even more preferable rangeis from 400 nm to 800 nm, and a yet even more preferable range is from400 nm to 600 nm.

By setting the density of the resin included in the second fiber to arange of 1 g/cm³ to 2 g/cm³, the compressive strength of the secondfiber can be increased. An example of the resin with a density of 1g/cm³ to 2 g/cm³ includes an epoxy resin.

By setting the average diameter of the second fiber to a range of 30 nmor more and less than 5 μm, the heat conductivity of the porous layercan be reduced. Further, it becomes possible to reduce the pressure lossof the porous layer. Therefore, the porous layer including the secondfiber has high compressive strength and low heat conductivity. A morepreferable range is from 400 nm to 800 nm, and an even more preferablerange is from 400 nm to 600 nm.

The thermal conductivities of the first fiber and the second fiber witha density of 1 g/cm³ to 2 g/cm³ are, for example, within a range of 0.01W/m·K to 5 W/m·K. Here, the heat conductivity of the resin that composethe fiber is defined as a heat conductivity of fiber. The heatconductivity of the fiber including an epoxy resin is from 0.01 W/m·K to5 W/m·K.

The porosity of the porous layer including at least one of the firstfiber and the second fiber is preferably within a range of 45% to 95%.An increase in porosity enables the heat-insulating properties of theporous layer to be increased. More preferably, the porosity is within arange of 70% to 95%.

The porosity of the stack including plural porous layers is desirablywithin a range of 45% to 95%. An increase in porosity enables theheat-insulating properties of the porous layers to be improved. Morepreferably, the porosity is within a range of 70% to 95%.

A porosity P₁(%) of the porous layer is calculated from Formula (1)below.P ₁(%)={(V ₁ −V ₂)×100}/V ₁  (1)

In Formula (1), V₁ represents a volume of the porous layer with thepores included, and is calculated from Formula (2) below based on alongitudinal length L₁ of the porous layer, a horizontal length L₂ ofthe porous layer, and a thickness L₃ of the porous layer. The volume V₁including the pores of the porous layer is measured in a state in whichthe porous layer is not filled with a material such as a liquid. In thecase that the porous layer is filled with a material such as a liquid,the measurement is performed after the material is removed by, forexample, washing the porous layer. Each of the dimensions L₁, L₂, and L₃is measured with a scale in a state where a porous layer produced on asubstrate or support is removed from the substrate or support, andthereafter, the porous layer is placed on a flat surface.V ₁ =L ₁ ×L ₂ ×L ₃  (2)

V₂ represents a net volume of the porous layer, and is obtained bydividing the weight of the porous layer by the density of the porouslayer.

A porosity P₂(%) of the stack is calculated from Formula (3) below.P ₂(%)={(V ₃ −V ₄)×100}/V ₃  (3)

In Formula (3), V₃ represents a stack volume which includes the pores ofthe stack, and is calculated from Formula (4) below based on alongitudinal length L₄ of the stack, a horizontal length L₅ of thestack, and a thickness L₆ of the stack. Stack volume V₃ including thepores of the stack is measured in a state in which the stack is notfilled with a material such as a liquid. In the case where the stack isfilled with a material such as a liquid, the measurement is performedafter the material is removed by, for example, washing the stack. Eachof the dimensions L₄. L₅, and L₆ is measured with a scale in a state inwhich the stack is placed on a flat surface.V ₃ =L ₄ ×L ₅ ×L ₆  (4)

V₄ is a net volume of the stack and is obtained by dividing the weightof the stack by the density of the stack.

The average diameters of the first fiber and the second fiber aremeasured by, for example, the method described below. The porous layeris observed with a scanning electron microscope (SEM). In this case, theporous layer is observed from a direction indicated by an arrow shown inFIG. 6. All diameters of the fibers in focus within the obtained imageare measured. Here, the diameter of the fiber is the length of the shortside in the projection view of the fiber with respect to the observationdirection indicated by the arrow of FIG. 6. FIG. 16 shows a projectionview 33 of a fiber 31 obtained by projecting the fiber 31 in theobservation direction indicated by an arrow 32. In the example of FIG.16, the projection view 33 is rectangular. A length L of the short sideof the rectangular projection view 33 is defined as a diameter of thefiber 31. The average calculated from the obtained measured values isdefined as an average diameter of the fiber. In this regard, theobservation area and magnification are changed so that the number offibers whose diameter is measurable is 10 or more.

The structural body of the embodiment may include a stack includingplural porous layers. For the stack, integrating of the porous layers bypressing, binding the porous layers together with a container member,and the like may be performed. Examples using the container memberinclude fitting the stack into a frame, disposing a plate-like member onthe outermost layer of the stack and thereby sandwiching the stack, andhousing the stack in a box-like container, a bag (e.g., the coveringmember 12), or the like.

The structural body of the embodiment may include a support. It ispreferable that the support is superior in mechanical strength to theporous layer. Thus, by putting the support into contact with the corecomposed of the porous layer or fiber, the porous layer can bereinforced. Thereby, the deformation of the porous layer due tocompression can be suppressed, and the shape of the structural body canbe maintained stably. The support desirably has a porous structure.Accordingly, the weight of the support can be reduced, and in turn, theweight of the structural body can be reduced. The support preferably hasa shape with angular portions rounded. Thus, it is possible to relax theforce applied from the angular portions of the support to the containermember. The support may be composed of, for example, an acrylic resinmaterial.

The porous layer including at least one of the first fiber or the secondfiber is produced by, for example, the electrospinning method. A mainthermosetting resin agent and an electrolyte are dispersed or dissolvedin an organic solvent to prepare a raw material solution that includesthe main thermosetting resin agent and the electrolyte. A curing agentis added to the raw material solution and then preliminarily cured byheating. Using the preliminarily cured raw material, a porous layer isformed by the electrospinning method. A substrate is earthed and used asan earth electrode. The raw material solution is charged by the voltageapplied to a spinning nozzle, and the charge amount per unit volume ofthe raw material solution increases due to volatilization of the solventfrom the raw material solution. The volatilization of the solvent and aresulting increase in charge amount per unit volume occur continuously.The raw material solution discharged from the spinning nozzle thusspreads in a longitudinal direction and deposits on the substrate as anano-sized thermosetting resin-including fiber. Coulomb force isgenerated between the thermosetting resin-including fiber and thesubstrate due to a potential difference between the nozzle and thesubstrate. Accordingly, the nano-sized thermosetting resin-includingfiber enables the contact area with the substrate to be increased andthe thermosetting resin-including fiber can be deposited on thesubstrate by the Coulomb force.

By including the electrolyte in the raw material solution, thedielectric constant and electrical conductivity of the raw materialsolution can be increased. As a result, the raw material solution can besufficiently charged voltage is applied to the raw material solution.Thus, controlling the fiber to have a target diameter, controlling thearrangement of the fibers, and the like becomes easy. Setting thedielectric constant of the thermosetting resin within a range of 1 to1000 contributes to improvement in the dielectric constant of the rawmaterial solution. Thus, control of the fiber formation becomes evenmore easy.

As the organic solvent included in the raw material solution, the abovedescribed kinds of organic solvents may be used.

As the substrate, the support may be used or one different from thesupport may be used. In the case of using one different from thesupport, the porous layer formed on the substrate is used after beingseparated from the substrate. Examples of the substrate include paperand aluminum foil.

FIGS. 2 and 3 show an example of the structural body of the embodiment.The structural body shown in FIG. 2 includes a stack 3 and a sac-likecontainer member 4 in which the stack 3 is housed. The stack 3 includesplural supports 1 and plural porous layers 2. The support 1 has a porousstructure, and may have the structure shown in FIG. 4 or 5. The support1 shown in FIG. 4 is a metal mesh porous sheet. On the other hand, thesupport 1 shown in FIG. 5 is a lattice type porous sheet. Both of thesheets have R-shaped corners. In the stack 3, the supports 1 and theporous layers 2 are alternately stacked, and porous layers 2 arepositioned at both of the outermost layers. The sac-like containermember 4 is, for example, one obtained by processing a laminate filminto a sac-like shape by heat sealing. Positioned at the side walls ofthe container member 4 are portions 5 where laminate films are adheredtogether by heat sealing. As the laminate film one can be used, forexample, which includes a layer including aluminum or aluminum alloy anda resin layer. A specific example of the laminate film is shown in FIG.8, but is not limited thereto. The laminate film 4 shown in FIG. 8 has afive-layered structure of from a first layer that composes the externalsurface of the container member 4 to a fifth layer that composes theinner surface of the container member 4. Polyethylene terephthalate(PET) is used for a first layer 4 a, polyamide (PA) is used for a secondlayer 4 b, a vapor-deposited aluminum layer is used for a third layer 4c, an ethylene-vinyl alcohol copolymer resin (EVOH) is used for a fourthlayer 4 e, and polyethylene (PE) is used for a fifth layer 4 d. In thestack shown in FIG. 2, as long as the supports 1 and the porous layers 2are alternately disposed, the support 1 may be disposed on one outermostlayer and the porous layer 2 disposed on the other outermost layer, oralternatively, supports 1 may be disposed on both of the outermostlayers.

The structural body shown in FIG. 3 has the same structure as that ofFIG. 2 except that they differ in the arrangement of the supports 1 andthe porous layers 2 in the laminate 3. In the stack 3, the porous layers2 are disposed on both of the outermost layers of plural supports 1 thatare stacked. One or two or more of the porous layers 2 may be disposedon each of the outermost layers.

Although the structural bodies shown in FIGS. 2 and 3 include thecontainer member and the supports, the container member and the supportsneed not be included. For example, as shown in FIG. 6, a stack 6 ofplural porous layers 2 may be used as a structural body of the firstembodiment. As shown in FIG. 7, the stack 6 shown in FIG. 6 may behoused in the container member 4. In FIG. 7, the same reference numeralsare given to the same members as those in FIGS. 2 and 3 and thedescription thereof is abbreviated.

By including the internal structure in the stack of the structural bodyas illustrated in FIGS. 2 and 3, deformation of the porous layers due tocompression is suppressed. Thus, crushing of pores can be furtherreduced. Accordingly, the compressive strength of the stack can furtherbe increased. As a result of improving the compressive strength, theamount of the fiber used for the porous layers can be reduced and theporosity can be increased. Thus, the structure can be made to have thinfiber diameter and high porosity, thereby further reducing the heatconductivity of the stack.

As illustrated in FIG. 2, when porous layers and supports arealternately disposed, a porous layer is positioned between the supports,and thus, the radiation heat transfer can be suppressed. Further, theheat conduction through the supports can be reduced by the porouslayers.

On the other hand, by disposing the support between the porous layers asillustrated in FIG. 3, the structure of the stack can be simplified andeasily produced.

The structural body of the embodiment can be used as a heat-insulatingelement, a biomaterial sheet, an insulating material, an insulatingauxiliary material, a water droplet impact absorbing member, an adhesivelayer, a barrier membrane or the like, in addition to the applicationsas described above.

In the case of the biomaterial sheet, examples of a substrate, on whichthe support or porous layer is formed, include a container such as apetri dish made of glass or resin, an adhesive bandage substrate, asheet, and a porous body (e.g., one in the form of film or sponge, andwhich retains a liquid). Examples of the adhesive bandage substrateinclude urethane non-woven fabrics, vinyl chloride sheets, elasticcotton cloths, sponge sheets, urethane films, and olefin films.

FIG. 9 shows an example using a container, such as a petri dish, as thesubstrate. As shown in FIG. 9, an oriented collagen sheet 16 is placedin a petri dish 15, and the top of the oriented collagen sheet 16 isfilled with a culturing medium 17. FIG. 10 shows an example of theoriented collagen sheet 16. The oriented collagen sheet 16 can beobtained, for example, by using a biomaterial such as collagen in placeof a thermosetting resin such as an epoxy resin.

The porous layer, stack, or structural body of the embodiment can beused as an insulating material and/or an insulating auxiliary material.As illustrated in FIG. 11, a porous layer 19 impregnated with aninsulating resin 20 can also be used as an insulating material and/or aninsulating auxiliary material 18. As a material that composes the fiber,which can be used in place of, or in combination with the thermosettingresin, examples include polycarbonate (PC), polyether sulphone (PES),polyacrylonitrile (PAN), polyethylenenaphthalate (PEN), polyurethane(PU), urea-formaldehyde resin (UF), acrylic resin (PMMA), polyamide(PA), polystyrene (PS), polyimide (PI), and polyamide-imide (PAI).

The porous layer, the stack or the structural body of the embodiment canbe used as a water droplet impact absorbing member. Examples of asubstrate on which the support or the porous layer is temporarily formedinclude substrates made of resin, such as fiber reinforced plastics(FRP). An example is shown in FIGS. 12 and 13. FIG. 12 shows a mainsection including blades 21 of a wind turbine. Further, FIG. 13 shows across-sectional view taken along line XIII-XIII of the blade 21. Asshown in FIG. 13, a surface of the blade 21 of the wind turbine can becovered with a porous layer 22. Accordingly, it is possible to relax theimpact when droplets such as water drops hit the blade 21. As thematerial that composes the fiber, another resin can be used in place of,or in combination with the thermosetting resin. Examples of anotherresin include the same resins listed for the insulating material and theinsulating auxiliary material.

Further, the porous layer, the stack, and the structural body of theembodiment can be used as an adhesive layer. As a result, the adhesivelayer can be thinly and uniformly formed on the substrate. Furthermore,by filling or impregnating the pores of the porous layer in the adhesivelayer with another adhesive agent, the adhesiveness of the adhesivelayer can be improved. Alternatively, an ink, a magnetic material, orthe like may be held in the pores the porous layer. Examples of asubstrate on which the support or the porous layer is temporarily formedinclude thin substrates used for printing, such as paper, photographs,film, sheets, or the like. As a material that composes the adhesivelayer, which can be used in place of, or in combination with thethermosetting resin, examples include aqueous adhesive agents,elastomeric adhesive agents, epoxy adhesive agents, cyano acrylicadhesive agents, vinyl adhesive agents, silicone rubber adhesive agents,and plastic adhesive agents. FIG. 14 shows an example in which a porouslayer 24 as the adhesive layer is disposed between substrates 23 a and23 b such as paper.

The porous layer, the stack, or the structural body of the embodimentmay be formed on the surface of a barrier membrane used for gasseparation or vapor liquid separation. Thus, the strength, weatherresistance, and durability of the barrier membrane can be improved.Further, since the porous layer having fine fibers and high porosity isformed on the surface of the barrier membrane, the separation efficiencycan be improved. An example is shown in FIG. 15. A porous layer 26 isformed on one surface of a barrier membrane 25 used for gas separationor vapor liquid separation. As the material that composes the fiber ofthe porous layer 26, another resin can be used in place of, or incombination with the thermosetting resin. Examples of another resininclude those listed for the insulating material and the insulatingauxiliary material.

As the fiber included in the porous layer described above, an inorganicnanofiber processed by calcination (e.g., TiO₂, SnO₂, SiO₂, ZrO₂, Fe₂O₃,BaTiO₃, or NiFe₂O₄) or a carbon fiber can be used in place of, or incombination with the above kinds of fibers.

EXAMPLES

Hereinafter, examples will be described in detail with reference to thedrawings.

Example 1

To a main epoxy resin agent which had been diluted to 50 wt % with asolvent: N.N-dimethylformamide (DMF), 1 wt % of LiBr was added anddissolved to prepare a solution. To this solution, 40 wt % of curingagent with respect to the amount of main epoxy resin agent was added.The resultant mixture was preliminarily cured by heating to 70° C. and araw material solution was obtained.

The obtained raw material solution was supplied from a spinning nozzleto the surface of a substrate using a metering pump at a supply rate of1 mL/h. A high voltage generator was used to apply a voltage of 60 kV tothe spinning nozzle. While conveying the substrate at a rate of 0.15/minand moving the spinning nozzle within a 200 mm distance perpendicular tothe conveying direction of the substrate, a fiber was deposited on thesurface of the substrate to form a porous layer. Aluminum foil was usedas the substrate.

The fiber that compose the obtained porous layer included 99 wt % ofepoxy resin and 1 wt % of LiBr. The epoxy resin had a density of 1.2g/cm³ and a dielectric constant of 11. Since the heat conductivity ofthe epoxy resin is defined as the heat conductivity of the fiber, theheat conductivity of the fiber is 0.3 W/m·K. The average diameter of thefibers was measured by the above method under SEM at 2000 timesmagnification, where the number of fibers whose diameter had beenmeasured was 20, and the resulting average diameter was 800 nm. Theporosity of the porous layer measured by the above method was 78%. Theporous layer had a longitudinal length of 150 mm, a horizontal length of150 mm, and a thickness of 21 mm.

As a support, a porous plate made of acrylic resin (polymethylmethacrylate: PMMA) having the structure shown in FIG. 5, a longitudinallength of 150 mm, a horizontal length of 150 mm, a thickness of 10 mm,and a porosity of 80% was prepared.

As shown in FIG. 2, porous layers and supports were alternately stackedto obtain a stack in which a porous film was positioned at both of theoutermost layers. Specifically, 30 stacked porous layers were defined asone unit, and three units and two supports were alternately stacked toobtain a stack. The number of layered porous layers in the stack was 90and the number of layered supports was 2. However, the number of layeredporous layers and the number of layered supports are not limitedthereto. The porosity of the stack was 80%.

The obtained stack was housed in a sac-like container member made oflaminate film. After that, the interior of the container member was putin a vacuum state using a vacuum pump, and the container member wassealed by heat sealing to obtain a structural body. The laminate filmhas a 5-layered structure shown in FIG. 8. As the first layer 4 a, a 16μm thick polyethylene terephthalate (PET) layer is used. As the secondlayer 4 b, a 30 μm thick polyamide (PA) layer is used. As the thirdlayer 4 c, a vapor-deposited aluminum layer with a thickness of lessthan 1 μm is used. As the fourth layer 4 e, a 20 μm thick ethylene-vinylalcohol copolymer resin (EVOH) layer is used. As the fifth layer 4 d, a60 μm thick polyethylene (PE) layer is used.

The heat conductivity of the obtained structural body of Example 1measured with a thermal conductivity meter was 7 mW/m·K.

Example 2

A porous layer and a support produced in the same manner as in Example 1were prepared. As shown in FIG. 3, the porous layers were stacked onboth of the outermost layers of the support 1 to obtain a stack. Thenumber of stacked layers of the porous layer was 10 per one side of thesupport. The porosity of the stack was 80%. The obtained stack washoused in a sac-like container member made of laminate film having thesame 5-layered structure as that of Example 1. After that, the inside ofthe container member was put in a vacuum state using a vacuum pump andthe container member was sealed by heat sealing to obtain a structuralbody.

The heat conductivity of the obtained structural body of Example 2measured with a thermal conductivity meter was 6 mW/m·K.

Example 3

As a support, a porous plate made of acrylic resin having the structureshown in FIG. 4, a longitudinal length of 150 mm, a horizontal length of150 mm, a thickness of 5 mm, and a porosity of 80% was prepared.

A raw material solution prepared in the same manner as in Example 1 wassupplied from a spinning nozzle to a substrate using a metering pump ata supply rate of 1 mL/h. A high voltage generator was used to apply avoltage of 60 kV to the spinning nozzle. While conveying the substrateat a rate of 0.15/min and moving the spinning nozzle within a 200 mmdistance perpendicular to the conveyance direction of the substrate, afiber was deposited on the surface of the substrate to form a porouslayer. Aluminum foil was used as the substrate.

The fiber that compose the obtained porous layer included 99 wt % ofepoxy resin and 1 wt % of LiBr. The epoxy resin had a density of 1.2g/cm³ and a dielectric constant of 11. Since the heat conductivity ofthe epoxy resin is defined as the heat conductivity of the fiber, theheat conductivity of the fiber is 0.3 W/m·K. The average diameter of thefibers was measured by the above method under SEM at 2000 timesmagnification, where the number of fibers whose diameter had beenmeasured was 20, and the resulting average diameter was 800 nm. Theporosity of the porous layer measured by the above method was 80%. Theporous layer had a longitudinal length of 150 mm, a horizontal length of150 mm, and a thickness of 21 mm.

As shown in FIG. 2, porous layers and supports were alternately stackedto obtain a stack in which a porous film was positioned at both of theoutermost layers. The number of layered porous layers in the stack was50 per one unit of stacked porous layers. The porosity of the stack was80%.

The obtained stack was housed in a sac-like container member made oflaminate film having the same 5-layered structure as that of Example 1.After that, the inside of the container member was put in a vacuum stateusing a vacuum pump and the container member was sealed by heat sealingto obtain a structural body.

The heat conductivity of the obtained structural body of Example 3measured with a thermal conductivity meter was 7 mW/m·K.

Example 4

A porous layer and a support produced in the same manner as in Example 3were prepared. As shown in FIG. 3, the porous layers were stacked onboth of the outermost layers of the support 1 to obtain a stack. Thenumber of stacked layers of the porous layer was 10 per one side of thesupport. The porosity of the stack was 92%.

The obtained stack was housed in a sac-like container member made oflaminate film having the same 5-layered structure as that of Example 1.After that, the inside of the container member was put in a vacuum stateusing a vacuum pump and the container member was sealed by heat sealingto obtain a structural body.

The heat conductivity of the obtained structural body of Example 4measured with a thermal conductivity meter was 6 mW/m·K.

Example 5

A porous layer was formed in the same manner as in Example 1 except that0.1 wt % of LiCl was used as an electrolyte in place of LiBr.

The fiber that compose the obtained porous layer included 99.9 wt % ofepoxy resin and 0.1 wt % of LiCl. The density and dielectric constant ofthe epoxy resin, the heat conductivity and average diameter of thefiber, the porosity of the porous layer, and the longitudinal length,horizontal length, and thickness of the porous layer were the same asthose of Example 1. Among these, a part of the data is shown in Table 1.

A structural body was produced in the same manner as in Example 1 exceptthat the obtained porous layer was used. The heat conductivity of thestructural body measured with a thermal conductivity meter is shown inTable 1.

Example 6

A porous layer was formed in the same manner as in Example 1 except that0.1 wt % of benzyl-triethylammonium chloride was used as an electrolytein place of LiBr.

The fiber that compose the obtained porous layer included 99.9 wt % ofepoxy resin and 0.1 wt % of benzyl-triethylammoniumchloride. The densityand dielectric constant of the epoxy resin, the heat conductivity andaverage diameter of the fiber, the porosity of the porous layer, and thelongitudinal length, horizontal length, and thickness of the porouslayer were the same as those of Example 1. Among these, a part data isshown in Table 1.

A structural body was produced in the same manner as in Example 1 exceptthat the obtained porous layer was used. The heat conductivity of thestructural body measured with a thermal conductivity meter is shown inTable 1.

Example 7

A porous layer was formed in the same manner as in Example 1 except thata main epoxy resin agent diluted to 45 wt % with a solvent:N,N-dimethylformamide (DMF) was used to adjust the average diameter ofan epoxy resin-include fiber to 450 nm in the electrospinning step. Thedensity and dielectric constant of the epoxy resin, the heatconductivity of the fiber, and the longitudinal length, horizontallength, and thickness of the porous layer were the same as those ofExample 1. The porosity of the porous layer and the porosity of thestack are shown in Table 1.

A structural body was produced in the same manner as in Example 1 exceptthat the obtained porous layer was used. The heat conductivity of thestructural body measured with a thermal conductivity meter is shown inTable 1.

Example 8

Polystyrene was dissolved in a solvent: N,N-dimethylformamide (DMF) toprepare a 20 wt % solution. The prepared solution was used as a rawmaterial solution.

The obtained raw material solution was supplied from a spinning nozzleto the surface of a substrate using a metering pump at a supply rate of1 mL/h. A high voltage generator was used to apply a voltage of 60 kV tothe spinning nozzle. While conveying the substrate at a rate of 0.15/minand moving the spinning nozzle within a 200 mm distance perpendicular tothe conveyance direction of the substrate, a fiber was deposited on thesurface of the substrate to form a porous layer. Aluminum foil was usedas the substrate.

The fiber that compose the obtained porous layer included 100 wt % ofpolystyrene. The density and dielectric constant of polystyrene, theheat conductivity and average diameter of the fiber, and the porosity ofthe porous layer are shown in Table 1. The longitudinal length,horizontal length, and thickness of the porous layer were the same asthose of Example 1.

As the support, the same acrylic resin porous plate as that of Example 1was prepared.

A stack and a structural body were produced in the same manner as inExample 1. The porosity of the stack and the heat conductivity of thestructural body measured with the thermal conductivity meter are shownin Table 1.

Example 9

30% of polyamide-imide was dissolved in a solvent: N,N-dimethylacetamide(DMAc) to prepare a 30 wt % solution. The prepared solution was used asa raw material solution.

The obtained raw material solution was supplied from a spinning nozzleto the surface of a substrate using a metering pump at a supply rate of1 mL/h. A high voltage generator was used to apply a voltage of 60 kV tothe spinning nozzle. While conveying the substrate at a rate of 0.15/minand moving the spinning nozzle within a 200 mm distance perpendicular tothe conveyance direction of the substrate, a fiber was deposited on thesurface of the substrate to form a porous layer. Aluminum foil was usedas the substrate.

The fiber that compose the obtained porous layer included 100 wt % ofpolyamide-imide. The density and dielectric constant of polyamide-imide,the heat conductivity and average diameter of the fiber, and theporosity of the porous layer are shown in Table 1. The longitudinallength, horizontal length, and thickness of the porous layer were thesame as those of Example 1.

As the support, the same acrylic resin porous plate as that of Example 1was prepared.

A stack and a structural body was produced in the same manner as inExample 1. The porosity of the stack and the heat conductivity of thestructural body measured with the thermal conductivity meter are shownin Table 1.

Comparative Example

A porous sheet formed of glass fiber was prepared. The porous sheet hada longitudinal length of 150 mm, a horizontal length of 150 mm, and athickness of 1 mm. The density of the glass was 2.5 g/cm³. Since theheat conductivity of the glass is defined as the heat conductivity ofthe fiber, the heat conductivity of the fiber is 1 W/m·K. The averagediameter of the fiber measured in the same manner as in Example 1 was 5μm. The porosity of the porous layer measured by the above method was95%.

23 porous sheets were stacked to obtain a stack. The porosity of thestack was 92%. The obtained stack was housed in a sac-like containermember made of laminate film having the same 5-layered structure as thatof Example 1. After that, the inside of the container member was put ina vacuum state using a vacuum pump and the container member was sealedby heat sealing to obtain a structural body.

The heat conductivity of the obtained structural body of Comparativeexample measured with a thermal conductivity meter was 8 mW/m·K.

Regarding the structural bodies of Examples 1 to 9 and Comparativeexample, a stack was formed by stacking the fiber membrane layer so asto have a thickness of about 150 μm, and the displacement and reactionforce were measured while pressing the stack with a contact pressuregauge (force gauge). The measurement results were plotted with thethickness of the stack on a horizontal axis and the reaction force on avertical axis. A slope of the straight line obtained by connecting theresultant plots is shown in Table 1 as the compressive strength.

TABLE 1 Density Heat Average Porosity of Dielectric ConductivityDiameter of Resin Resin Constant of Fiber of Fiber Porous of Fiber(g/cm³) of Resin (W/m · K) (nm) Layer (%) Example 1 Epoxy 1.2 11 0.3 800nm 78 resin Example 2 Epoxy 1.2 11 0.3 800 nm 78 resin Example 3 Epoxy1.2 11 0.3 800 nm 80 resin Example 4 Epoxy 1.2 11 0.3 800 nm 80 resinExample 5 Epoxy 1.2 11 0.3 800 nm 78 resin Example 6 Epoxy 1.2 11 0.3800 nm 78 resin Example 7 Epoxy 1.2 11 0.3 450 nm 82 resin Example 8Polystyrene 1.05 2.5 0.15 800 nm 85 Example 9 Polyamide 1.4 5 0.4 1200nm  80 imide Comparative Glass 2.5 5 1  5 μm 95 Example Fiber PorosityStructure of Struc- of Heat Compressive Stack ture Internal ConductivityStrength (%) Electrolyte of Stack Support (mW/m · K) (kPa/mm) Example 180 LiBr FIG. 2 FIG. 5 7 −1551 Example 2 80 LiBr FIG. 3 FIG. 5 6 −1551Example 3 80 LiBr FIG. 2 FIG. 4 7 −1551 Example 4 92 LiBr FIG. 3 FIG. 46 −1551 Example 5 80 LiCl FIG. 2 FIG. 5 7 −1551 Example 6 80 Benzyl-FIG. 2 FIG. 5 7 −1551 triethyl- ammonium chloride Example 7 82 LiBr FIG.2 FIG. 5 6 −1551 Example 8 80 — FIG. 2 FIG. 5 15 −1126 Example 9 80 —FIG. 2 FIG. 5 10 −1300 Comparative 92 — — — 8 −1700 Example

As is apparent from Table 1, the structural bodies of Examples 1 to 7produced using epoxy resin have low heat conductivity, compared to thestructural bodies of Examples 8 and 9 and Comparative example. Thestructural bodies of Examples 1 to 7 produced using epoxy resin aresuperior in compressive strength, compared to the structural bodies ofExamples 8 and 9 produced using another resin material and have low heatconductivity.

According to the structural body of at least one of the aboveembodiments and examples, includes a porous layer including anelectrolyte and a first fiber that includes a thermosetting resin and/ora second fiber that includes a resin with a density of 0.5 g/cm³ to 3g/cm³ and has an average diameter of 30 nm to 5 μm. Accordingly, astructural body capable of arbitrarily changing the compressive strengthcan be provided.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

The invention claimed is:
 1. A structural body, comprising at least oneporous layer that includes a fiber including an electrolyte and athermosetting resin, wherein the thermosetting resin is a component witha highest proportion among a plurality of components of the fiber, thethermosetting resin is an epoxy resin, and an amount of the electrolytein the fiber ranges from 0.01 wt % to 10 wt %.
 2. The structural bodyaccording to claim 1, wherein the electrolyte is lithium bromide.
 3. Thestructural body according to claim 1, wherein the fiber has an averagediameter of 30 nm to 5 μm.
 4. The structural body according to claim 1,wherein a dielectric constant of the thermosetting resin is within arange of 1 to 1000.